/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package clojure.asm;

/**
 * A constant pool item. Constant pool items can be created with the 'newXXX'
 * methods in the {@link ClassWriter} class.
 *
 * @author Eric Bruneton
 */
final class Item{

/**
 * Index of this item in the constant pool.
 */
int index;

/**
 * Type of this constant pool item. A single class is used to represent all
 * constant pool item types, in order to minimize the bytecode size of this
 * package. The value of this field is one of {@link ClassWriter#INT},
 * {@link ClassWriter#LONG}, {@link ClassWriter#FLOAT},
 * {@link ClassWriter#DOUBLE}, {@link ClassWriter#UTF8},
 * {@link ClassWriter#STR}, {@link ClassWriter#CLASS},
 * {@link ClassWriter#NAME_TYPE}, {@link ClassWriter#FIELD},
 * {@link ClassWriter#METH}, {@link ClassWriter#IMETH}.
 * <p/>
 * Special Item types are used for Items that are stored in the ClassWriter
 * {@link ClassWriter#typeTable}, instead of the constant pool, in order to
 * avoid clashes with normal constant pool items in the ClassWriter constant
 * pool's hash table. These special item types are
 * {@link ClassWriter#TYPE_NORMAL}, {@link ClassWriter#TYPE_UNINIT} and
 * {@link ClassWriter#TYPE_MERGED}.
 */
int type;

/**
 * Value of this item, for an integer item.
 */
int intVal;

/**
 * Value of this item, for a long item.
 */
long longVal;

/**
 * First part of the value of this item, for items that do not hold a
 * primitive value.
 */
String strVal1;

/**
 * Second part of the value of this item, for items that do not hold a
 * primitive value.
 */
String strVal2;

/**
 * Third part of the value of this item, for items that do not hold a
 * primitive value.
 */
String strVal3;

/**
 * The hash code value of this constant pool item.
 */
int hashCode;

/**
 * Link to another constant pool item, used for collision lists in the
 * constant pool's hash table.
 */
Item next;

/**
 * Constructs an uninitialized {@link Item}.
 */
Item(){
}

/**
 * Constructs an uninitialized {@link Item} for constant pool element at
 * given position.
 *
 * @param index index of the item to be constructed.
 */
Item(final int index){
	this.index = index;
}

/**
 * Constructs a copy of the given item.
 *
 * @param index index of the item to be constructed.
 * @param i     the item that must be copied into the item to be constructed.
 */
Item(final int index, final Item i){
	this.index = index;
	type = i.type;
	intVal = i.intVal;
	longVal = i.longVal;
	strVal1 = i.strVal1;
	strVal2 = i.strVal2;
	strVal3 = i.strVal3;
	hashCode = i.hashCode;
}

/**
 * Sets this item to an integer item.
 *
 * @param intVal the value of this item.
 */
void set(final int intVal){
	this.type = ClassWriter.INT;
	this.intVal = intVal;
	this.hashCode = 0x7FFFFFFF & (type + intVal);
}

/**
 * Sets this item to a long item.
 *
 * @param longVal the value of this item.
 */
void set(final long longVal){
	this.type = ClassWriter.LONG;
	this.longVal = longVal;
	this.hashCode = 0x7FFFFFFF & (type + (int) longVal);
}

/**
 * Sets this item to a float item.
 *
 * @param floatVal the value of this item.
 */
void set(final float floatVal){
	this.type = ClassWriter.FLOAT;
	this.intVal = Float.floatToRawIntBits(floatVal);
	this.hashCode = 0x7FFFFFFF & (type + (int) floatVal);
}

/**
 * Sets this item to a double item.
 *
 * @param doubleVal the value of this item.
 */
void set(final double doubleVal){
	this.type = ClassWriter.DOUBLE;
	this.longVal = Double.doubleToRawLongBits(doubleVal);
	this.hashCode = 0x7FFFFFFF & (type + (int) doubleVal);
}

/**
 * Sets this item to an item that do not hold a primitive value.
 *
 * @param type    the type of this item.
 * @param strVal1 first part of the value of this item.
 * @param strVal2 second part of the value of this item.
 * @param strVal3 third part of the value of this item.
 */
void set(
		final int type,
		final String strVal1,
		final String strVal2,
		final String strVal3){
	this.type = type;
	this.strVal1 = strVal1;
	this.strVal2 = strVal2;
	this.strVal3 = strVal3;
	switch(type)
		{
		case ClassWriter.UTF8:
		case ClassWriter.STR:
		case ClassWriter.CLASS:
		case ClassWriter.TYPE_NORMAL:
			hashCode = 0x7FFFFFFF & (type + strVal1.hashCode());
			return;
		case ClassWriter.NAME_TYPE:
			hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
			                                * strVal2.hashCode());
			return;
			// ClassWriter.FIELD:
			// ClassWriter.METH:
			// ClassWriter.IMETH:
		default:
			hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
			                                * strVal2.hashCode() * strVal3.hashCode());
		}
}

/**
 * Indicates if the given item is equal to this one.
 *
 * @param i the item to be compared to this one.
 * @return <tt>true</tt> if the given item if equal to this one,
 *         <tt>false</tt> otherwise.
 */
boolean isEqualTo(final Item i){
	if(i.type == type)
		{
		switch(type)
			{
			case ClassWriter.INT:
			case ClassWriter.FLOAT:
				return i.intVal == intVal;
			case ClassWriter.TYPE_MERGED:
			case ClassWriter.LONG:
			case ClassWriter.DOUBLE:
				return i.longVal == longVal;
			case ClassWriter.UTF8:
			case ClassWriter.STR:
			case ClassWriter.CLASS:
			case ClassWriter.TYPE_NORMAL:
				return i.strVal1.equals(strVal1);
			case ClassWriter.TYPE_UNINIT:
				return i.intVal == intVal && i.strVal1.equals(strVal1);
			case ClassWriter.NAME_TYPE:
				return i.strVal1.equals(strVal1)
				       && i.strVal2.equals(strVal2);
				// ClassWriter.FIELD:
				// ClassWriter.METH:
				// ClassWriter.IMETH:
			default:
				return i.strVal1.equals(strVal1)
				       && i.strVal2.equals(strVal2)
				       && i.strVal3.equals(strVal3);
			}
		}
	return false;
}
}
